Verifying molecular structures and bonding in ethane and ammonia

Steps:

• Examine statement 1: Ethane formula C₂H₆ has 6 H atoms; ammonia NH₃ has 3 H atoms; 6 is twice 3, so correct.
• Examine statement 2: Nitrogen (atomic number 7) has electron configuration [He] 2s² 2p³, confirming 5 valence electrons in unreacted atom, so correct.
• Examine statement 3: Ammonia has N-H single covalent bonds; each shares 2 electrons (1 from N, 1 from H), so correct.
• All statements true, matching option A.

Why A is correct:

• Molecular formulas and valence electron rules confirm all three statements align with covalent bonding principles.

Why the others are wrong:

• B omits statement 3, but covalent bond definition includes shared electron pairs.
• C omits statement 2, but nitrogen's 5 valence electrons are fixed by atomic structure.
• D omits statement 1, but ethane's C₂H₆ formula has exactly twice the H atoms of NH₃.

Final answer: A